Organization of No. 1 ESS Central Processor

Telephone central offices must cover a wide range of sizes and provide a large variety of services to customers; in addition, they must be compatible with existing systems, adaptable to varied and changing operating conditions, dependable, reliable, and economical. The development of an electronic switching system capable of satisfying these requirements presented many new problems to the designers. As a result, many techniques new to the telephone switching field were introduced in the system. 1 One of the most important new techniques is the control philosophy, which utilizes a stored program. A system employing a stored program is one which consists of memories for storing both instructions and data, and a logic unit which monitors and controls peripheral equipment by performing a set of operations dictated by a sequence of program instructions. The stored program philosophy permitted the designers to use centralized logic circuitry and large-capacity memory units as a means of attaining flexibility and over-all economy in the system. 1845